Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-03-29
2001-07-31
Hall, Carl E. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603120, C029S603140, C029S603250
Reexamination Certificate
active
06266868
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combination type thin film magnetic head having a writing inductive type thin film magnetic head and a reading thin film magnetic head including a magnetoresistive element, said heads being stacked on a substrate, and a manufacturing method thereof.
2. Explanation of the Related Art
Recently, a surface recording density of a hard disk drive has been improved, and the performance of a combination type thin film magnetic head has to be improved accordingly.
As a combination type thin film magnetic head, a head having an inductive type thin film magnetic head for writing and a magnetoresistive type thin film magnetic head for reading, which are stacked one on the other on a substrate, has been proposed and has been put to practical use. In general, an element using a conventional anisotropic magnetoresistive (AMR) effect has been used as a reading magnetoresistive element. Still, an element using a giant magnetoresistive (GMR) effect, which has a larger resistance variation ratio than the AMR element by several times, has been developed.
In this specification, the AMR element and the GMR element or the like are referred to as a magnetoresistive type thin film magnetic head generically, or simply an MR element.
The surface recording density of several giga (G) bits per inch 2 can be realized by using the AMR element. Moreover, the surface recording density can be more improved by using the GMR element. In this way, the realization of a hard disk drive device in 10 G byte or more becomes possible by raising the surface recording density.
One of factors for determining the performance of the reproducing head including such a magnetoresistive reproduction element is a height of the magnetoresistive reproduction element (MR height MRH). The MR height MRH is a distance of the magnetoresistive reproduction element whose edge is exposed to an air bearing surface measured from the air bearing surface. In the manufacturing process of the thin film magnetic head, desired MR height MRH is obtained by controlling an amount of polishing when the air bearing surface is polished.
On the other hand, in accordance with the improvement in the performance of the reproducing head, the performance of the recording head is required to be improved. It is necessary to raise the density of the truck on a magnetic recording medium in order to improve the surface recording density. For this purpose, it is necessary to make the width of a write gap on the air bearing surface narrow from several microns to the sub-micron order. The semiconductor processing technology is used to achieve this.
A throat height (TH) is one of the factors for deciding the performance of the writing thin film magnetic head. The throat height is a distance of a magnetic pole portion measured from the air bearing surface to an edge of an insulating layer by which a thin film coil is separated electrically, and it is desired to shorten this distance as much as possible. Reduction in size of the throat height TH is also decided by the polishing amount on the air bearing side.
Therefore, in order to improve the performance of the combination type thin film magnetic head, that is, one that includes stacked reading magnetoresistive type and writing inductive type thin film magnetic heads, it is important to make the writing inductive type thin film magnetic head and the reading magnetoresistive type thin film magnetic head well balanced.
FIGS. 1-9
show successive steps of manufacturing a conventional standard thin film magnetic head, in each figure, A is a cross sectional view of the entire thin film magnetic head, and B is a cross sectional view of the magnetic pole portion. Moreover,
FIGS. 10-12
are a cross sectional of the entire conventional completed thin film magnetic head, a cross sectional view of the magnetic pole portion, and a plan view of the entire thin film magnetic head, respectively. In this embodiment, the thin film magnetic head is a combination type formed by stacking the readout inductive type thin film magnetic head and the reading MR reproduction element.
At first, as shown in the
FIG. 1
, an insulating layer
2
consisting of, for example, alumina (Al
2
O
3
) is deposited on a substrate
1
made of AlTiC in the thickness of about 5-10 &mgr;m. Next, as shown in the
FIG. 2
, a first magnetic layer
3
constituting one magnetic shield protecting a MR reproduction element of a reproducing head from the influence of the external magnetic field is formed with the thickness of 3 &mgr;m.
Then, as shown in the
FIG. 3
, after alumina is deposited by sputtering with the thickness of 100-150 nm, as an insulating layer
4
, a magnetoresistive layer
5
made of a material having the magnetoresistive effect and constituting the MR reproduction element, is formed with the thickness of 10 nm or less, and then, is formed into a desired shape with a mask alignment of high accuracy.
Then, as shown in
FIG. 4
, another insulating layer
6
is formed such that the magnetoresistive layer
5
is embedded between the insulating layers
4
and
6
.
Next, as shown in
FIG. 5
, a second magnetic layer
7
made of a permalloy is formed with a film thickness of 3 &mgr;m. The second magnetic layer
7
not only functions as the other shield for magnetically shielding the MR reproduction element together with the first magnetic layer
3
, but also functions as one pole of the writing thin film magnetic head.
Next, after a write gap layer
8
made of a non-magnetic material, for example, alumina, is formed with a thickness of about 200 nm on the second magnetic layer
7
, a magnetic layer made of a magnetic material having a high saturation magnetic flux density, for example, permalloy (Ni: 50 wt %, Fe: 50 wt %) and nitride iron (FeN), is formed. This magnetic layer is shaped into a desired form with a mask alignment of high accuracy to obtain a pole chip
9
. The track width is defined by a width W of the pole chip
9
. Therefore, it is necessary to narrow the width W of the pole chip
9
in order to achieve a high surface recording density.
In this case, a dummy pattern
9
′ for connecting the second magnetic layer
7
with a third magnetic layer constituting the other pole, is formed at the same time. Then, after mechanical polishing or chemical mechanical polishing (CMP), a through-hole can be formed easily.
In order to prevent the effective write track width from being widened, that is, in order to prevent the magnetic flux from being widened at one pole during the data writing, the gap layer
8
in surroundings of pole chip
9
and the second magnetic layer
7
constituting the other pole are etched by the ion beam etching such as the ion milling. This state is shown in FIG.
5
. This structure is called as a trim structure, and this portion becomes a magnetic pole portion of the second magnetic layer.
Next, as shown in
FIG. 6
, after forming an insulating layer
10
such as an alumina film having a thickness of about 3 &mgr;m, the surface is flattened by for example CMP.
Afterwards, after an electrically insulating photoresist layer
11
is formed to a predetermined pattern by the mask alignment with high accuracy, a first layer thin film coil
12
of, for example, copper is formed on the photoresist layer
11
.
Then, as shown in
FIG. 7
, after forming an insulating photoresist layer by the mask alignment with high accuracy on the thin film coil
12
, the surface is flattened by baking at the temperature of, for example, 250-300° C.
In addition, as shown in
FIG. 8
, a second layer thin film coil
14
is formed on the flattened surface of the photoresist layer
13
. Next, after forming a photoresist layer on the thin film coil
12
by the mask alignment with high accuracy, the surface is flattened by baking at the temperature of, for example, 250° C.
As described above, the reason for forming the photoresist layers
11
,
13
, and
15
by the mask alignment with high accuracy is to define the throat height TH and the MR height MRH by using
Hall Carl E.
Oliff & Berridg,e PLC
TDK Corporation
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